Two tiny spheres carrying charges of $1.5$ µC and $2.5$ µC are located $30$ cm apart. What is the potential at a point $10$ cm from the midpoint in a plane normal to the line and passing through the mid-point?

The diagrams below show regions of equipotential. 
      
A positive charge is moved from $\mathrm{A}$ to $\mathrm{B}$ in each diagram. Choose the correct statement from the options given below:

Consider a uniform electric field in the $z\text-$direction. The potential is a constant:

 
Choose the correct from the given options:

In a region, the potential is represented by $V=(x,y,z)=6x-8xy-8y+6yz,$ where $V$ is in volts and $x,y,z$ are in meters. The electric force experienced by a charge of $2$ coulomb situated at a point $(1,1,1)$ is:
1. $6\sqrt{5}~\text{N}$
2. $30~\text{N}$
3. $24~\text{N}$
4. $4\sqrt{35}~\text{N}$

In a certain region of space with volume $0.2~\text m^3,$ the electric potential is found to be $5~\text V$ throughout. The magnitude of the electric field in this region is:
1. $0.5~\text {N/C}$ 
2. $1~\text {N/C}$ 
3. $5~\text {N/C}$ 
4. zero

The electric field at the origin is along the positive $x\text-$axis. A small circle is drawn with the centre at the origin cutting the axes at points $\mathrm A$, $\mathrm B$, $\mathrm C$ and $\mathrm D$ having coordinates $(a,0),(0,a),(-a,0),(0,-a)$ respectively. Out of the points on the periphery of the circle, the potential is minimum at:
1. $\mathrm A$
2. $\mathrm B$
3. $\mathrm C$
4. $\mathrm D$